Vortec 906 And 601 Flow Numbers Ported And Not/mild Ported.

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You are using an out of date browser. It may not display this or other websites correctly.You should upgrade or use an alternative browser. Vortec 906 and 601 flow numbers ported and not/mild ported.

• Thread starter jeff swisher
• Start date May 19, 2018
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jeff swisher

Veteran Member

Apr 26, 2018 2,103 Yukon Oklahoma I got my 906 casting vortec head back from the machine shop. Same shop and same SF600 flow bench that flowed my 601 heads. Those are 305HO heads. The Vortec heads came off a 1996 chevy truck Virgin. I did not do any valve or seat grinding all I did was a bowl port and thin the guides and lap the factory valves. Yes I did screw in studs and guide plates but that makes zero difference in flow. I will show numbers for 601 with mild porting no raised ex or intake runners and some much more ported 601's with same 1.84-1.50 valves. So numbers for you Radiused intake with clay and NO pipe on exhaust. stock 1.94-1.50 valves. 906 flow IN/EX..................601 mild porting....601 more porting. & stock 906 .200"...... 112/67..............97/76...................... 116/95..................127/93 .300"......175/109..............145/105.................166/127.................178/125 .400".......215/142..............182/124................199/159.................212/140 .450".......230.....................194. .500" ......244/168..............203/137................208/171.................228/144 .600" ......."BU"/177................206/147...............211/174..............224/146 Intake side backed up "BU" on the 906 at 510 lift. SF600 bench was generating some heat. I think I will see how thick the pushrod pinch is and may work it over in the 906 head and may do a bit more in the bowls and the single angle valve job of the ex port will get one angle added to it ..as of now it is just a 45 then straight into the bowl. But then again I just want to put these things on as is and run em. I pulled stock numbers from here for the 906 heads. http://speedtalk.com/forum/viewtopic.php?t=21448 The SF600 operator told me air temp in the flow room will make differences in how much the head will flow. It was flowed and the room was in the 80's and the SF600 was recording 125F temps when the exhaust side was done being flowed. I do not know what the box temps were on intake side.

jeff swisher

Veteran Member

Apr 26, 2018 2,103 Yukon Oklahoma I went ahead and raised the ex roof a bit more on the 906 heads. And opened the ex bowl a bit more and 30/45/60 degree valve job and opened the intake bowl a tick more in a couple areas and moved the short side back a tad more and opened the pushrod pinch .050" and blended it so the turn is not as abrupt. Did a little smoothing in the chamber where there is raised casting around the valve outer perimeter. Will drop heads off monday and hope he can get to them quicker than a week. If not eeehhh no biggie. Kind of want to see if the extra angles help the ex flow down low and if it still backs up on the intake side. 1

1980RS

Veteran Member

Jun 17, 2006 8,047 MN If you want 30 extra cfm on the intake side look up Joe Mondello's intake port mod it works. If you are talking a radius valve job they do not work to well on the intake port but well on the exhaust side. This site may earn a commission from merchant affiliate links like Ebay, Amazon, and others.

jeff swisher

Veteran Member

Apr 26, 2018 2,103 Yukon Oklahoma This is what I found on Mondello and Vortecs. http://www.superchevy.com/how-to/en...vrolet-engine-building-tips-you-need-to-know/

jeff swisher

Veteran Member

Apr 26, 2018 2,103 Yukon Oklahoma Got the heads back the 906 castings ..Flowed after some more work to them. Intake side still backed up and picked up minimal cfm. Exhaust side did better. Before and after numbers on the 906 Vortec heads will be below. Before was basic bowl blending and lapped valves stock valve job. After was more porting in bowls and runners and touched up the 3 angle valve job with same angles on intake side as stock and stuck a 3 angle on exhaust side and raised roof more and opened the bowl more. I did not cut valves just seats on the heads 30-45-60 then lapped lightly. Bowl blend CFM IN &EX........valve job and more porting. 200"...... 112/67....................112/82 .300"......175/109...................176/127 .350".......................................198/? .400".......215/142...................217/160 .450".......230/?........................233/? .500" ......244/168...................248/174 .550".........................................???/ 183 .600".........................................???/190 The exhaust responds well to massaging. Not bad for something I paid $35 each for. Cost me $40 each time I have it flowed.. starting to add up.. I best quit now. Some not so special pictures of the ports from my sony cybershot 3.2mp. Last edited: May 25, 2018 C

CNC BLOCKS

Veteran Member

Oct 11, 2004 1,656 NORTHEAST

jeff swisher said: Got the heads back the 906 castings ..Flowed after some more work to them. Intake side still backed up and picked up minimal cfm. Exhaust side did better. Before and after numbers on the 906 Vortec heads will be below. Before was basic bowl blending and lapped valves stock valve job. After was more porting in bowls and runners and touched up the 3 angle valve job with same angles on intake side as stock and stuck a 3 angle on exhaust side and raised roof more and opened the bowl more. I did not cut valves just seats on the heads 30-45-60 then lapped lightly. Bowl blend CFM IN &EX........valve job and more porting. 200"...... 112/67....................112/82 .300"......175/109...................176/127 .350".......................................198/? .400".......215/142...................217/160 .450".......230/?........................233/? .500" ......244/168...................248/174 .550".........................................???/ 183 .600".........................................???/190 The exhaust responds well to massaging. Not bad for something I paid $35 each for. Cost me $40 each time I have it flowed.. starting to add up.. I best quit now. Some not so special pictures of the ports from my sony cybershot 3.2mp. View attachment 58590 View attachment 58591 View attachment 58592 Click to expand...

jeff swisher said: I got my 906 casting vortec head back from the machine shop. Same shop and same SF600 flow bench that flowed my 601 heads. Those are 305HO heads. The Vortec heads came off a 1996 chevy truck Virgin. I did not do any valve or seat grinding all I did was a bowl port and thin the guides and lap the factory valves. Yes I did screw in studs and guide plates but that makes zero difference in flow. I will show numbers for 601 with mild porting no raised ex or intake runners and some much more ported 601's with same 1.84-1.50 valves. So numbers for you Radiused intake with clay and NO pipe on exhaust. stock 1.94-1.50 valves. 906 flow IN/EX..................601 mild porting....601 more porting. & stock 906 .200"...... 112/67..............97/76...................... 116/95..................127/93 .300"......175/109..............145/105.................166/127.................178/125 .400".......215/142..............182/124................199/159.................212/140 .450".......230.....................194. .500" ......244/168..............203/137................208/171.................228/144 .600" ......."BU"/177................206/147...............211/174..............224/146 Intake side backed up "BU" on the 906 at 510 lift. SF600 bench was generating some heat. I think I will see how thick the pushrod pinch is and may work it over in the 906 head and may do a bit more in the bowls and the single angle valve job of the ex port will get one angle added to it ..as of now it is just a 45 then straight into the bowl. But then again I just want to put these things on as is and run em. I pulled stock numbers from here for the 906 heads. http://speedtalk.com/forum/viewtopic.php?t=21448 The SF600 operator told me air temp in the flow room will make differences in how much the head will flow. It was flowed and the room was in the 80's and the SF600 was recording 125F temps when the exhaust side was done being flowed. I do not know what the box temps were on intake side. Click to expand...

Jeff I would not base everything on flow numbers as they is such as thing as quantity of flow and then quality of flow the Vortecs have quality of flow. The early Vortec 906 castings with the 170 runners may not have out flowed the old phase 2 Bowtie heads but on the dyno and on the circle track they out powered those old school heads. My 11:01 circle track engines .560 lift 250ish duration @ .050 always was in the 515 horse range and 470ish on the torque with a 1.94 X 1.500 valves Raised ports, Port bias, spark plug location is near the center of the cylinder as they call those the fast burn chamber. Don't base everything on flow numbers.................

jeff swisher

Veteran Member

Apr 26, 2018 2,103 Yukon Oklahoma Thank you sir. For a fact I do not base everything on flow numbers as I have made a lot of power and excellent ET with what we would call poor flow numbers 220 @.500" lift. I completely agree on shape makes a huge difference. This is a new shaped head for me to play with and I just can't leave it stock you know. The 2 times having it flowed was to see if i hurt it by doing a valve job or hurt it by blending the bowls. I know I should have tested on car first then tweaked them.. that's the way I did it 30 years ago. Never had things flowed.. I just cared about what they did on the car going down the road. 1

1980RS

Veteran Member

Jun 17, 2006 8,047 MN

jeff swisher said: Got the heads back the 906 castings ..Flowed after some more work to them. Intake side still backed up and picked up minimal cfm. Exhaust side did better. Before and after numbers on the 906 Vortec heads will be below. Before was basic bowl blending and lapped valves stock valve job. After was more porting in bowls and runners and touched up the 3 angle valve job with same angles on intake side as stock and stuck a 3 angle on exhaust side and raised roof more and opened the bowl more. I did not cut valves just seats on the heads 30-45-60 then lapped lightly. Bowl blend CFM IN &EX........valve job and more porting. 200"...... 112/67....................112/82 .300"......175/109...................176/127 .350".......................................198/? .400".......215/142...................217/160 .450".......230/?........................233/? .500" ......244/168...................248/174 .550".........................................???/ 183 .600".........................................???/190 The exhaust responds well to massaging. Not bad for something I paid $35 each for. Cost me $40 each time I have it flowed.. starting to add up.. I best quit now. Some not so special pictures of the ports from my sony cybershot 3.2mp. View attachment 58590 View attachment 58591 View attachment 58592 Click to expand...

Good job on the exhaust port there. The intake is more work like all heads, just make sure you do not cut that square portion out of the chamber like some folks do, it ruins the head. If you look at the intake port roof you will see the area pretty easy the you need to fix to get more flow from. Do a good 3 angle valve job and make sure you specify to the machinist NO INTERFERENCE VALVE JOB!!, It kills power, I found it out years ago the expensive way. On the exhaust side if the machinist has the cutter for a radius seat valve job do that as it work well on Chevy heads but not on the intake side.

jeff swisher

Veteran Member

Apr 26, 2018 2,103 Yukon Oklahoma Luckily I am doing the valve job on these. I had to look up Radiused seat valve job. Basically a smooth valve job like the shape of a velocity stack. Funny you mention that shape. It was about 2007 and a buddy wanted his 1991 or so corvette to be as quick and fast as my Nova I told him then sell the vette and get a Nova. I was serious. So he got a Nova and I stuck a 9" rear with spool and 456 gears under it and built his TH350 and built his engine a 4 bolt main, flat top with 355" and arp bolts everywhere. He said he was going to get AFR heads he just needed to save up. So I took the original 1978 Nova 305 2 barrel heads and ported them and lapped the valves to the stock valve job. But here is where it gets interesting the radiused valve job you speak of. I did a radiused smooth back cut on the valves. The intake and exhaust. I figured why not.. lets see if these 1.72-1.50 valves in these PURE JUNK 305 heads will work. I used an off the shelf comp magnum flat tappet hydraulic 280H with Z springs and cheap screw in studs the ones without the nut. Topped off the heads with a very old TR1YX and 2 600cfm edelbrock carbs that intake without carbs is 12" tall. He never raced at the track so we went and his first pass was 12.8 at 110 mph. Never flowed the heads ..did not care to they are what they are. flow tech headers and 3" pipe into warlock turbo mufflers dumped and the rear axle. 91 octane gas and 41 total timing. For junk it ran quite well. By the end of the night he figured out how much heat the MT 275-60-15 drag radials needed and went 12.51 @ 111 MPH a couple times. converter stalled to 2200 rpm. it was the holeshot 3000 B&M Fun stuff You must log in or register to reply here. Share: Facebook X (Twitter) Reddit Pinterest Tumblr WhatsApp Email Share Link

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